Guerbet alcohols are high molecular weight primary alcohols with high-purity beta branching. They have low volatility and lower irritation properties compared to other linear alcohols. The melting point and viscosity of Guerbet alcohols are also reduced compared to other linear alcohols. They exhibit oxidative stability at high temperatures and remain liquid up until hydrocarbon chains lengths of C20. Furthermore, Guerbet alcohols are reactive and can be used to make many derivatives, such as nonionic surfactants with a wide range of cloud points, which make them particularly suitable for many different petroleum industry operations. However, the products formed from Guerbet alcohols are predominantly used in the cosmetic industry.
The basic starting point of the Guerbet reaction is a fatty alcohol which undergoes self-condensation through the use of strong basis and/or catalysts such as copper or zinc oxide. The produced Guerbet alcohols are beta-branched primary alcohols with twice the molecular weight of the reactant alcohols minus water. The overall reaction for preparing Guerbet alcohols can be represented by the following equation:
wherein subscript indice n is a positive integer greater or equal to 2. For example, if subscript indice n is eleven (11), the reactant alcohol has twelve carbon atoms (C12) and the produced Guerbet alcohol has twenty-four carbon atoms (C24). Similarly, C16 alcohols (n=15) can be combined to make C32 Guerbet alcohols. Examples of catalysts that can be used in preparing Guerbet alcohols include nickel, lead salts, oxides of copper, lead, zinc, chromium, molybdenum, tungsten, manganese, palladium compounds, silver compounds, or combinations thereof. Depending on the type of Guerbet alcohol to be produced, dimerization of the reactant alcohol can be carried out at temperatures ranging between about 100° to 300° Celsius.
The table below shows scientific names of C6 to C44 Guerbet alcohols and their corresponding chemical formulas.
Guerbet AlcoholGuerbet Formula2-Methyl-1-pentanolC6H14O2-Ethyl-1-hexanolC8H18O2-Propyl-1-heptanolC10H22O2-Butyl-1-octanolC12H26O2-Pentyl-1-nonanolC14H30O2-Hexyl-1-decanolC16H34O2-Heptyl-1-undecanolC18H36O2-Octyl-1-dodecanolC20H42O2-Nonyl-1-tridecanolC22H46O2-Decyl-1-tetradecanolC24H50O2-Undecyl-1-pentadecanolC26H54O2-Dodecyl-1-hexadecanolC28H58O2-Tridecyl-1-heptadecanolC30H62O2-Tetradecyl-1-octadecanolC32H66O2-Pentadecyl-1-nonadecanolC34H70O2-Hexadecyl-1-eicosanolC36H74O2-Heptadecyl-1-heneicosanolC38H78O2-Octodecyl-1-docosanolC40H82O2-Nonadecyl-1-tricosanolC42H86O2-Eicosyl-1-tetraconsanolC44H90O
For most applications, such as for use in the cosmetics industry, Guerbet alcohols are produced in high purity by driving the reaction (e.g., Equation 1) to near completion. Any unreacted monomer alcohol can be “stripped-off” to further enhance the purity of the produced Guerbet alcohol. As a result, highly branched, high molecular weight primary alcohols with near mid-point branching (i.e., large hydrophobes with high-purity beta branching) are produced. Guerbet alcohols tend to be more expensive than other alcohols due to the comprehensive conversion during the alcohol dimerization process and/or the subsequent removal of unreacted monomer alcohol. Accordingly, the cost of producing Guerbet alcohols can be prohibitive, especially for applications needing large quantities of Guerbet alcohols.
Guerbet alcohols are utilized to manufacture the additives, which, for example, can be used as surfactants, wetting agents, emulsifiers, detergents and solubilizers. Surfactants are utilized in various stages of hydrocarbon recovery and processing, such as in drilling operations (e.g., drilling fluids/dispersants), reservoir injection (e.g., fracturing fluids, enhanced oil recovery fluids), well productivity (e.g., acidizing fluids), hydrocarbon transportation, environmental remediation, or a combination thereof. A well-known enhanced oil recovery (EOR) method uses surfactant polymer floods to recover additional oil from reservoirs. The compositions of chemicals used in enhanced oil recovery processes vary depending on the type, environment, and composition of the reservoir formation. Surfactants are commonly used when producing or transporting heavy or extra heavy oils, which generally have an API gravity of less than about 20 degrees API. As used herein, API gravity is the weight per unit volume of oil as measured by the American Petroleum Industries (API) scale. For example, API gravity can be measured according to the test methods provided by the American Society for Testing and Materials (ASTM) in test standard D287-92(2006). Crude oil having an API gravity of less than about 20 degrees API is generally referred to as heavy oil. Crude oil having an API gravity of less than about 10 degrees API is generally referred to as extra heavy oil.